Hair dye compositions are classified depending upon the types of dyes to be used or the presence or absence of a melanin bleaching action. Typical examples of the hair dye compositions include a two-agent type oxidative hair dye composition consisting of a first agent containing an alkali agent, an oxidation dye and an optional direct dye such as a nitro dye and a second agent containing an oxidizing agent; and one-agent type non-oxidative hair dye composition containing a pH adjuster (acid or alkali) and at least one of direct dye such as an acid dye, a basic dye and a nitro dye.
Patent Document 1 mentions that the incorporation of a specific cationic polymer having a high charge density and a specific anionic polysaccharide derivative having a low viscosity in these hair dyes and a hair cosmetic such as a shampoo, a hair treatment or a styling agent can attain high improving effect on finger combability and combability after treatment with the hair cosmetic.
Patent Document 2 discloses a technology of improving hair dyeability by combining a cationic polymer and a specific salt in a hair dye composition containing a specific azo dye, and it describes an anionic polymer as a water-soluble polymer which can be used.
(Patent Document 1) WO2014/196579
(Patent Document 2) WO2015/186815